Fossil-boffins probing into the remains of a soft-bodied tulip animal that lived in the Rockies 500 million years ago have just published a paper revealing the secrets of the weird creature.

Essentially stomachs on stalks, the tulip-shaped creatures known as Siphusauctum gregarium lived in great herds and are the most commonly found fossils in a fossil bed dating from the middle Cambrian period, when the Rockies were submerged under the oceans.

According to painstaking fossil-analysis by a team from the University of Toronto, the bulb-shaped stomachs grew up to 22cm, and connected to the seabed with little tentacles attached to the end of its stem. Its prominent bulb-shaped organ would have waved in the sea currents and expanded to draw water inside it, contracting to expel it out the top through a small anus.

The Siphusauctum gregarium was a filter-feeder, with its internal structure consisting almost entirely of intestine:

"Internal structures include a central and prominent sac-like gut enclosed by a tube representing the margins of the body cavity" explains the paper authored by Lorna J O'Brien and Jean-Bernard Cohen. "The gut differentiated into three main zones, an ovoid lower tract near the base of the calyx, grading into a bulbous mid-gut, then tapering into a straight and thin upper intestine projecting upwards to a central terminal anus."

It's likely the tulip creatures were buried under a mud slide along with a slice of other sea bed life about 500 million years ago to create the famous Middle Cambrian Burgess Shale fossil bed. The stalked stomach is another weird life form from the biological expansion known as the 'Cambrian explosion' a time when life on earth burgeoned wildly in diversity of form. ®

The paper A New Stalked Filter-Feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada by Lorna J. O'Brien and Jean-Bernard Caron is published by PLoS One in pdf.